.\"	$OpenBSD: cgthree.4,v 1.32 2012/08/18 08:44:25 jmc Exp $
.\"	$NetBSD: cgthree.4,v 1.4 1998/06/11 08:32:20 fair Exp $
.\"
.\" Copyright (c) 1992, 1993
.\"	The Regents of the University of California.  All rights reserved.
.\"
.\" This software was developed by the Computer Systems Engineering group
.\" at Lawrence Berkeley Laboratory under DARPA contract BG 91-66 and
.\" contributed to Berkeley.
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.\" modification, are permitted provided that the following conditions
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.\" 3. Neither the name of the University nor the names of its contributors
.\"    may be used to endorse or promote products derived from this software
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.\"	from: Header: cgthree.4,v 1.3 94/02/03 20:49:52 leres Exp
.\"     from: @(#)cgthree.4	8.2 (Berkeley) 2/16/94
.\"
.Dd $Mdocdate: August 18 2012 $
.Dt CGTHREE 4 sparc
.Os
.Sh NAME
.Nm cgthree
.Nd 8-bit color frame buffer
.Sh SYNOPSIS
.Cd "cgthree* at sbus?"
.Cd "cgthree* at obio0" Pq some sun4m models
.Cd "wsdisplay* at cgthree?"
.Sh DESCRIPTION
The
.Nm
is a color frame buffer, available as an SBus card or on-board on some sun4c
and sun4m workstations.
A small number of frame buffer SBus cards, not manufactured by
.Tn Sun ,
are cgthree-compatible and will also be recognized by the
.Nm
driver.
.Pp
The
.Nm
driver interfaces the frame buffer with the
.Xr wscons 4
console framework.
It does not provide direct device driver entry points
but makes its functions available via the internal
.Xr wsdisplay 4
interface.
.Sh DISPLAY RESOLUTION
.Ss Sun frame buffers
If the
.Nm
frame buffer is used as the console display, it is possible, for some models,
to select a different resolution than the default 1152x900 or 1024x768
by changing the OpenPROM environment.
To change the default resolution, type the following:
.Pp
.Em \   ok
setenv
.Em output-device
screen:r1152x900x66
.Pp
to change to a 66Hz 1152x900 resolution.
.Pp
If the
.Nm
frame buffer is a secondary display, or a serial console is used, the
display resolution can not be changed without using an
.Em nvramrc
OpenPROM script.
Refer to the
.Em Sun Frame Buffer FAQ
for details.
.Pp
The
.Nm
frame buffer accepts the following resolutions:
.Pp
.Bl -tag -width screen:r1280x1024x76 -compact
.It screen:r1024x768x77
Super VGA 1024x768, with a refresh rate of 77Hz.
This is the default setting on model 501-2691.
.It screen:r1152x900x66
Standard 1152x900, with a refresh rate of 66Hz.
This is the default setting on older models (501-1415 and 501-8044).
.It screen:r1152x900x76
Standard 1152x900, with a refresh rate of 76Hz.
This is the default setting on more recent models (501-1718 and 501-1909).
.El
.Pp
Note that not all models support settings other than their default setting.
.Ss Tritec GVC-1, Integrix SFB200
These frame buffers are cgthree-compatible cards with a VGA-compatible video
connector.
There are only two resolutions supported, selected by jumper JP2 on the card:
.Bl -column "short" "Resolution" -offset indent
.It Sy JP2 Ta Sy Resolution
.It Li "open" Ta "1024x768, 60Hz"
.It Li "short" Ta "1152x900, 66Hz"
.El
.Sh SEE ALSO
.Xr intro 4 ,
.Xr sbus 4 ,
.Xr wscons 4 ,
.Xr wsdisplay 4
.Rs
.%T Sun Frame Buffer FAQ
.%U http://www.sunhelp.org/faq/FrameBuffer.html
.Re
